Screamers have a poor fossil record. A putative Eocene specimen is known from Wyoming, while the more modern Chaunoides antiquus is known from the late Oligocene to early MioceneinBrazil. Anhimids are most similar to presbyornithids, with which they form a clade to the exclusion of the rest of Anseriformes. Given the presence of lamelae in the otherwise fowl-like beaks of screamers, it is even possible that they evolved from presbyornithid-grade birds, reverting from a filter-feeding lifestyle to an herbivorous one.[5]
The three species occur only in South America, ranging from Colombia to northern Argentina. The horned screamer was once present on the Caribbean island of Trinidad, but is now extirpated from there. They are large, bulky birds, with a small downy head, long legs and large feet which are only partially webbed. They have large spurs on their wings which are used in fights over mates and territorial disputes;[2] these can break off in the breast of other screamers, and are regularly renewed. Unlike ducks, they have a partial moult and are able to fly throughout the year.[2] They live in open areas and marshes with some grass and feed on water plants. One species, the southern screamer, is considered a pest as it raids crops and competes with farm birds.
Screamers typical lay 4–5 white eggs, with clutches ranging between 2 and 7 . Like most Anseriformes, the chicks can run as soon as they are hatched. They can swim better than they can run, so young screamers are usually raised in or near water, where they can better avoid predators. Like ducks, screamer chicks imprint early in life. That, and their unspecialized omnivorous diet makes them amenable to domestication. They can be excellent guard animals, due to their loud alarm calls ("screams") when encountering anything new and possibly threatening.
Both the southern and the horned screamer remain widespread and are overall fairly common.[6][7] In contrast, the northern screamer is relatively rare and consequently considered near threatened.[8] They are seldom hunted, in spite of their conspicuous nature, because their flesh has a spongy texture and is riddled with air-sacs, making it highly unpalatable.[citation needed] The main threats are habitat destruction and increased intensification of agriculture.[8]
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Carboneras, C. (1992). "Family Anhimidae (Screamers)". In del Hoyo, J.; Elliott, A.; Sargatal, J. (eds.). Handbook of the Birds of the World. Vol. 1, Ostrich to Ducks. Barcelona, ES: Lynx Edicions. pp. 528–535. ISBN84-87334-09-1.
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Todd, Frank S. (1991). Forshaw, Joseph (ed.). Encyclopaedia of Animals: Birds. London, UK: Merehurst Press. p. 87. ISBN1-85391-186-0.
Screamer videos. Internet Bird Collection (video shorts, sound recordings, and photographs). Archived from the original on 2016-04-11. Retrieved 2023-07-18.{{cite AV media}}: CS1 maint: unfit URL (link)
